[Bug libstdc++/52189] [4.7 regression] Relaxed gthreads check breaks Solaris 8/9 symbol versioning

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52189

--- Comment #4 from Jonathan Wakely <redi at gcc dot gnu.org> 2012-02-10 
11:31:22 UTC ---
i.e #undef _GLIBCXX_HAS_GTHREADS